1. Field of the Invention
This invention relates to a method of constructing a heat-insulating and water-proof structure. More particularly, it is concerned with a method of constructing a heat-insulating and water-proof structure by laying, but not securing a plurality of heat-insulating boards on a base surface, and by joining a plurality of water-proof membranes joined to one another so that each membrane covers one of the heat-insulating boards.
2. Description of the Prior Art
A lot of insulating and water-proof structures have been developed since lightweight roofing slabs became available. For example, it is well known to attach heat-insulating materials, in the form of foamed polyethylene or polyurethane membranes, to roofing slabs with an adhesive, and securing a large water-proof membrane to the insulating material with an adhesive. The adhesive is employed on both sides of the heat-insulating material. This method involves a number of drawbacks which cannot be avoided unless a high level of skill is employed in construction work. The water-proof membrane wrinkles and swells easily when using the adhesive. In addition, specks of the adhesive formed when it is applied or dries makes it difficult for the water-proof membrane to adhere uniformly to the heat-insulating material.
In order to improve these drawbacks, there has been developed a fastening method which does not employ any adhesive. According to this method, a water-proof sheet is secured to a heat-insulating material by fastening means such as screws, nails, rubber members or holding bars. The heat-insulating material is secured to a roof deck, and the fastening means are covered with rubber strips or membranes. Although this method has overcome the drawbacks which are caused by the adhesive, it still has a number of other drawbacks. Those portions of the water-proof membrane which are secured by the fastening means to the heat-insulating material are likely to be pulled away from the heat-insulating material by wind pressure or other external forces. As a result, these forces in conjuction with the fastening means subject the water-proof member to height stresses and the water-proof membrane is easily torn by the fastening means which secure it to the heat-insulating material. Moreover, the fastening means, and the rubber strips or membranes covering them, protrude from the water-proof sheet and impair the appearance of the structure. Furthermore, it is impossible to remove any wrinkle that has formed in the water-proof membrane.